KR20130131000A - Display device and driving method thereof - Google Patents

Abstract

The present invention relates to a display device and a driving method thereof, capable of preventing damage due to overheat in a data driving unit and a signal control unit. The display device according to one embodiment of the present invention includes: a display panel which includes a plurality of gate lines, a plurality of data lines, and a pixel which is connected to the gate line and the data line; a gate driving unit which supplies a gate signal to the gate line; the data driving unit which supplies a data signal to the data line; and the signal control unit which controls the gate signal and the data signal. The signal control unit includes a data changing unit which changes the gradation of image data if a gradation difference of the image data between two adjacent pixels connected to the same data line among the data lines is a first threshold value or more. [Reference numerals] (612) Data mapping unit;(614) Data comparison unit;(616) Tone correction unit

Description

DISPLAY DEVICE AND DRIVING METHOD THEREOF [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention [0002] The present invention relates to a display device and a driving method thereof, and more particularly to a display device and a driving method thereof that can prevent breakage due to overheating of a data driver and a signal controller.

Display devices are required for computer monitors, televisions, mobile phones, etc., which are widely used today. The display device includes a cathode ray tube display device, a liquid crystal display device, and a plasma display device.

2. Description of the Related Art A liquid crystal display device is one of the most widely used flat panel display devices and is composed of two display panels in which electric field generating electrodes such as a pixel electrode and a common electrode are formed and a liquid crystal layer interposed therebetween, To generate an electric field in the liquid crystal layer, thereby determining the orientation of the liquid crystal molecules in the liquid crystal layer and controlling the polarization of the incident light to display an image.

Such a liquid crystal display device includes a display panel and a signal control section. The signal control unit transmits the image data of the screen to be displayed on the display panel and the control signal for driving the display panel to the display panel through the gate driver and the data driver to drive the display device.

In the display panel, a plurality of gate lines and a plurality of data lines are formed so as to cross each other, and pixels connected to the gate lines and the data lines are formed. The gate line is connected to the gate driver to receive the gate signal, and the data line is connected to the data driver to receive the data signal.

When the data voltages applied to the adjacent pixels among the plurality of pixels connected to the same data line are similar, the swing width of the voltage controlled by the data driver is not large. On the other hand, when the difference between the data voltages applied to the adjacent pixels is large, the swing width increases, which may increase the temperature of the data driver.

The data driver may be damaged due to the temperature rise of the data driver, and the signal controller for controlling the signal applied to the data driver may be overheated.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problems, and it is an object of the present invention to provide a display device capable of determining whether or not a pattern of a pixel is likely to overheat a data driver, And a driving method thereof.

Accordingly, it is an object of the present invention to provide a display device and a driving method thereof that can prevent the data driver and the signal controller from being overheated to prevent breakage.

According to an aspect of the present invention, there is provided a display device including a display panel including a plurality of gate lines, a plurality of data lines, and pixels connected to the gate lines and the data lines; A gate driver for supplying a gate signal to the gate line; A data driver for supplying a data signal to the data line; And a signal control unit for controlling the gate signal and the data signal, wherein the signal control unit controls the first and second data lines so that the difference in gradation of image data of two adjacent pixels, which are connected to the same data line among the plurality of data lines, The gradation of the image data is converted into a gradation of the image data.

Wherein the data conversion unit counts the number of times when a difference between gradations of image data of two adjacent pixels connected to the same data line is equal to or greater than the first threshold value and determines whether the number is equal to or greater than a second threshold value A comparator; And a gradation correcting unit for converting the gradation of the image data when the number is greater than or equal to the second threshold value.

Wherein the data comparator compares the gray level of one of the two adjacent pixels when the gray level of the pixel is equal to or greater than the 1-1 threshold value and the gray level of the other pixel is equal to or less than the 1-2 threshold value, Wherein when a gradation of one pixel is equal to or less than a first threshold value and a gradation of the other pixel is equal to or greater than a first threshold value and a difference between gradations of image data of two adjacent pixels is equal to or greater than a first threshold value .

And the grayscale correction unit may correct the grayscale of the image data having the grayscale exceeding the third threshold value to the third threshold value when the number is greater than or equal to the second threshold value.

The gradation correction section may sequentially reduce the gradation of the image data having the gradation exceeding the third threshold value for a plurality of frames to correct the gradation value to the third threshold value.

The data comparator may compare the gradation of the entire image data of one frame to count the number of gradations, and the gradation corrector may convert the gradation of the image data of the next frame when the number is greater than or equal to the second threshold value.

The data driver may include a plurality of data drivers, and the data comparator may count the number of the plurality of data drivers.

And the grayscale correction unit may convert grayscale of the video data when the number of the data drivers in any one of the plurality of data drivers is equal to or greater than the second threshold value.

When the pixels are arranged in a staggered arrangement with respect to the data lines, the data comparing unit may compare the difference in gradation of image data of two pixels adjacent to each other in the diagonal direction, and count the number of gradations in the diagonal direction equal to or larger than the first threshold value.

The data conversion unit may further include a data mapping unit for rearranging the image data of two pixels adjacent to each other in the diagonal direction so that the image data is adjacent to each other in the data line direction when the pixels are arranged in zigzags with respect to the data line.

According to another aspect of the present invention, there is provided a method of driving a display device, comprising: counting the number of gradations of image data of two adjacent pixels connected to the same data line among a plurality of data lines, Determining whether the number is greater than or equal to a second threshold value; Converting the gradation of the image data if the number is greater than or equal to the second threshold value; And outputting the converted image data.

When the number is less than the second threshold value, the image data can be output without converting the gradation of the image data.

Counting the number of times when the difference between the gradations of the image data of the two adjacent pixels is equal to or greater than the first threshold value and the gradation of any one of the two adjacent pixels is equal to or greater than the 1-1 threshold value, And when the gradation of one pixel is equal to or less than the first threshold value and when the gradation of one of the two adjacent pixels is equal to or less than a first threshold value, It can be determined that the difference in gradation of the image data of the two adjacent pixels is equal to or greater than the first threshold value.

The gradation of the image data having the gradation exceeding the third threshold may be corrected to the third threshold value when the number of gradations is equal to or greater than the second threshold value in the step of converting the gradation of the image data.

The gradation of the image data having the gradation exceeding the third threshold value may be sequentially reduced for a plurality of frames and corrected to the third threshold value in the step of converting the gradation of the image data.

Counting the number of gradations of all the image data of one frame and counting the number of gradations of the image data of the two adjacent pixels to convert the gradation of the image data, The gradation of the image data of the next frame can be converted when the number is equal to or larger than the second threshold value.

Wherein the plurality of data lines are divided and connected to a plurality of data drivers, and in the step of counting the number of cases in which the difference in gradation of the image data of two adjacent pixels is equal to or greater than the first threshold value, Each drive can be counted.

The gradation of the image data can be converted when the number of the data drivers in any one of the plurality of data drivers is equal to or greater than the second threshold value in the gradation conversion of the image data.

Wherein the display device includes a plurality of pixels connected to the data line, and in the step of counting the number of gradations of the gradations of the image data of the two adjacent pixels that are equal to or greater than the first threshold value, In a case where the data lines are arranged in a zigzag manner, differences in gradation of image data of two pixels adjacent to each other in the diagonal direction may be compared, and the number of cases in which the gradation is greater than or equal to the first threshold value may be counted.

Wherein the display device includes a plurality of pixels connected to the data line and before the step of counting the number of gradations of the gradation of the image data of the two adjacent pixels being equal to or greater than the first threshold value, And arranging the image data of two pixels adjacent to each other in the diagonal direction so as to be adjacent to each other in the data line direction when the data lines are arranged in a zigzag manner with respect to the data line.

The display device and the driving method as described above have the following effects.

The display device and the driving method thereof according to an embodiment of the present invention determine whether a pattern of a pixel is likely to overheat the data driver, and when there is a concern of overheating, There is an effect that overheat of the driving unit and the signal control unit can be prevented.

In addition, there is an effect that it is possible to prevent breakage due to overheating of the data driver and the signal controller.

1 is a block diagram of a display device according to an embodiment of the present invention.
2 is a block diagram illustrating a signal controller of a display device according to an embodiment of the present invention.
3 is a flowchart illustrating a method of driving a display device according to an embodiment of the present invention.
FIG. 4 is a graph showing a result of comparing the gradation of each pixel with the 1-1th threshold value and the 1-2th threshold value in a display device according to an embodiment of the present invention.
5 is a graph showing a result of comparing the gradation of each pixel with the 1-1 th threshold value and the 1-2 th threshold value in another display apparatus according to an embodiment of the present invention.
6 to 13 are diagrams showing various patterns that cause overheating of the data driver.
FIG. 14 is a graph showing a plurality of patterns of temperatures according to the number of data lines connected to the data driver.
15 is a graph showing the temperature of the data driver according to the correction of the maximum gradation in a horizontal stripe pattern in which rows composed of pixels having the maximum gradation and rows composed of pixels having the smallest gradation are alternately repeated.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

In the drawings, the thickness is enlarged to clearly represent the layers and regions. Like parts are designated with like reference numerals throughout the specification. It will be understood that when an element such as a layer, film, region, plate, or the like is referred to as being "on" another portion, it includes not only the element directly over another element, Conversely, when a part is "directly over" another part, it means that there is no other part in the middle.

First, a display device according to an embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a block diagram of a display apparatus according to an embodiment of the present invention, and FIG. 2 is a block diagram illustrating a signal controller of a display apparatus according to an embodiment of the present invention.

The display apparatus according to an embodiment of the present invention includes a display panel 300 including a plurality of pixels, a signal controller 600 for controlling signals for driving the display panel, signals for driving the display panel 300, And a gate driver 400 and a data driver 500. [

The display panel 300 includes a plurality of gate lines G1 to Gn and a plurality of data lines D1 to Dm and a plurality of gate lines G1 to Gn extending in the horizontal direction, The gate electrodes D1 to Dm extend in the vertical direction while crossing the plurality of gate lines G1 to Gn.

The display panel 300 includes a pixel PX connected to the gate lines G1-Gn and the data lines D1-Dm and one pixel PX includes the gate lines G1-Gn and data lines D1- And a switching element connected to the data lines D1-Dm. The control terminal of the switching element is connected to the gate lines G1 to Gn, the input terminal is connected to the data lines D1 to Dm, and the output terminal is connected to the liquid crystal capacitor and the storage capacitor.

The display panel 300 includes a first substrate on which gate lines G1-Gn, data lines D1-Dm, a pixel PX, a switching element and the like are formed, a second substrate facing the first substrate, And a liquid crystal layer interposed between the first substrate and the second substrate.

Although the display panel 300 is described as being a liquid crystal display panel, the present invention is not limited thereto, and various display panels such as an organic light emitting display panel, an electrophoretic display panel, and a plasma display panel may be used.

The signal controller 600 controls the gate driver 400, the data driver 500, and the like. The signal controller 600 receives image data and a control signal for controlling the display thereof from an external graphic controller (not shown). Video data may contain the brightness (luminance) information of the pixels (PX), the luminance is, for given suhyo, for example 1024 (= 2 ^10), 256 (= 2 ⁸⁾ or 64 (= 2 ⁶⁾ gradations (gray) Lt; / RTI > Examples of the control signal include a vertical synchronization signal Vsync, a horizontal synchronization signal Hsync, a main clock signal MCLK, and a data enable signal DE.

The signal controller 600 appropriately processes the image data in accordance with the operation condition of the display panel 300 based on the control signal and generates the gate control signal CONT1 and the data control signal CONT2, CONT1 to the gate driver 400 and the video data processed with the data control signal CONT2 to the data driver 500.

The gate driver 400 is connected to the gate lines G ₁ -G _n of the display panel 300 and supplies a gate signal composed of a combination of the gate-on voltage Von and the gate-off voltage Voff to the gate lines G ₁ - G _n ).

The data driver 500 is connected to the data lines D _{1 to} D _m of the display panel 300 and supplies a voltage corresponding to the gray level of the image data received from the signal controller 600 as a data voltage to the data lines D _1- D _m . At this time, the data driver 500 refers to the gamma data and determines the gamma voltage corresponding to the gradation of the image data as the data voltage.

Each of these driving devices 400, 500, 600 may be directly mounted on the display panel 300 in the form of at least one integrated circuit chip or mounted on a flexible printed circuit film (not shown) And may be attached to the liquid crystal panel assembly 300 in the form of a tape carrier package (TCP) or mounted on a separate printed circuit board (not shown). Alternatively, these driving devices 400, 500 and 600 may be integrated in the display panel 300 together with the signal lines G ₁ -G _n , D ₁ -D _m and switching elements. In addition, the drivers 400, 500, 600 may be integrated into a single chip, in which case at least one of them, or at least one circuit element that makes up these, may be outside a single chip.

2, the signal controller 600 includes a data converter 610 for determining whether a pixel pattern of the frame is a pattern that may overheat the data driver 500, and converting the gradation of the image data do.

Data conversion section 610 includes a plurality of data lines (D ₁ -D _m), the difference between the same data lines (D ₁ -D _m), the two pixels (PX) video data (RGB) of an adjacent one another connected to the gray level of the A data comparison section 614 for counting the number of cases where the number of the image data is equal to or larger than the first threshold value and determining whether the number is equal to or larger than the second threshold value, And a gray level correction unit 616.

That is, the image data (RGB) applied to the data converting unit 610 undergoes a comparison and judgment process in the data comparing unit 614, and when the predetermined condition is satisfied, the gray level correcting unit 616 converts the image data RGB, And outputs the converted image data R'G'B '.

The data comparing unit 614 has a threshold made up of the 1-1 th threshold value and the 1-2 th threshold value. In the display device composed of 256 gradations, the 1-1 threshold value can be set to a value close to 256 gradations, and the 1-2 threshold value can be set to a value close to 0 gradation.

The data comparator 614 compares two adjacent pixels PX (1) to PX (2) when the grayscale of one of the two adjacent pixels is equal to or greater than the 1-1th threshold value and the grayscale of the other pixel is equal to or less than the 1-2 ) Is equal to or greater than the first threshold value. When the gradation of any one of two adjacent pixels is equal to or less than the first threshold value and the gradation of the other pixel is equal to or greater than the first threshold value, RGB) is equal to or greater than the first threshold value.

That is, the data comparison unit 614 determines that the difference of the gradation of the two pixels is large when one of the two adjacent pixels has a value close to the minimum gradation and the other pixel has a value close to the maximum gradation .

The data comparing unit 614 compares the gradations of the entire image data of one frame and counts the number of gradations of the image data RGB of the two adjacent pixels PX that are greater than or equal to the first threshold value.

When the number of cases in which the difference between the gradations of the image data RGB of the two adjacent pixels PX is equal to or greater than the first threshold value is less than the second threshold value as a result of the comparison and the determination of the data comparison unit 614, 616 output the gray level of the video data RGB without modification. When the number of cases in which the difference between the gradations of the image data RGB of the two pixels PX adjacent to each other is equal to or greater than the first threshold value is equal to or greater than the second threshold value, Converts the data (RGB) and outputs the converted image data (R'G'B ').

In this case, the first threshold value, the 1-1th threshold value, the 1-2th threshold value, and the second threshold value can be appropriately set in consideration of the degree of influence on the data driver 500. For example, the first threshold value can be set to 220 gradations, the 1-1th threshold value can be set to 20 gradations, the 1-2th threshold value can be set to 240 gradations, and the second threshold value can be set to 50. [

The data comparing unit 614 compares the gradations of the entire image data of one frame and counts the number of gradations of the image data RGB of the two adjacent pixels PX that are greater than or equal to the first threshold value.

The gradation correction unit 616 corrects the gradation of the image data having the gradation exceeding the third threshold value to the third threshold value. It is preferable that the third threshold is set to such a degree that the change of the gradation is not visually recognized. For example, the third threshold value can be set to 250 gradations.

The gray level corrector 616 may correct the gray level of the image data having the gray level exceeding the third threshold value immediately to the third threshold value in the next frame when the number of gray level levels higher than the first threshold value is equal to or higher than the second threshold value.

Alternatively, the gradation correction unit 616 may sequentially correct the gradation. That is, the gradation correction unit 616 can sequentially reduce the gradation of the image data having the gradation exceeding the third threshold value for a plurality of frames and correct it to the third threshold value.

A plurality of data drivers 500 may be formed as shown in FIG. At this time, the data comparison unit 614 may count the number of the data drivers 500. In addition, the gray level corrector 616 can convert the gray level of the image data RGB if the number of the plurality of data drivers 500 in the data driver 500 is equal to or greater than the second threshold value.

The data conversion unit 610 may further include a data mapping unit 612. The data mapping unit 612 can rearrange the position of the video data.

When a plurality of pixels PX connected to the same data lines D ₁ -D _m are arranged in the same direction, the data comparator 614 compares the gradation differences between adjacent pixels arranged in the same column do. On the other hand, when a plurality of pixels PX connected to the same data line are arranged in a zigzag manner, the data comparator 614 must compare gradation differences between pixels adjacent to each other in the diagonal direction.

Accordingly, in the latter case, the data mapping unit 612 can rearrange the positions of the image data so that the data comparison unit 614 can compare the gradation differences between adjacent pixels arranged in the same column as in the former case . That is, when the pixels PX are arranged in zigzags with respect to the data lines D ₁ -D _m , the data mapping unit 612 supplies the video data of the two pixels PX adjacent to each other in the diagonal direction to the data lines D ₁ -D _m ). ≪ / RTI >

Hereinafter, a driving method of a display apparatus according to an embodiment of the present invention will be described with reference to the drawings.

3 is a flowchart illustrating a method of driving a display device according to an embodiment of the present invention. FIG. 4 is a graph showing a result of a comparison between a gray level and a threshold value of each pixel in a display device according to an embodiment of the present invention.

As shown in Fig. 3, C (t) representing the number of cases in which the difference in gradation of image data of two adjacent pixels connected to the same data line is equal to or larger than the first threshold value is reset to zero. (S100) Here, t represents the order of the data driver. The number of cases in which the gradation difference between adjacent pixels in the first data driver is equal to or larger than the first threshold value is denoted by C (1) The number of cases in which the gradation difference between adjacent pixels is equal to or larger than the first threshold value is denoted by C (t).

Next, the gradation of each pixel is compared with the first-first threshold value G_h and the first-second threshold value G_l. (S110) gray scale (G _n) of the n-th pixel is the first-first threshold (G_h) or more and, the n-th pixel and the data line connected to the same gray level of adjacent pixels of the (n + 1) th pixels (G _{n + 1} ) is equal to or less than the first-second threshold value G_l. It is also judged whether or not the gradation Gn of the n-th pixel is equal to or less than the first-second threshold G_l and the gradation Gn + 1 of the (n + 1) th pixel is equal to or greater than the 1-1th threshold G_h do. If either of the above two cases is true, a new C (t) is generated by adding 1 to the existing C (t). (S120)

That is, the number of cases in which any one of the adjacent pixels connected to the same data line is equal to or greater than the 1-1th threshold value G_h and the other pixel is equal to or less than the 1-2th threshold value G_l is counted .

Then, it is determined whether or not one frame has ended. If not, the processes of S110 and S120 are repeated. (S130) That is, the same method is used to compare the gradations of the entire image data of one frame and count the number.

Hereinafter, with reference to FIG. 4, it is assumed that any one of adjacent pixels connected to the same data line D is equal to or greater than the 1-1th threshold value G_h and the other pixel is equal to the 1-2th threshold value (G_l) or less will be described as an example.

4 includes two data drivers 500. One data driver 500 is connected to 12 data lines D and four data lines D are connected to one data line D, (PX) are connected.

Of course, the number of the data driver 500, the data line D, and the pixel PX is only an example for explanation, and the number thereof can be changed according to the resolution of the display device. For example, the data driver 500 may be connected to various numbers of data lines D such as 366, 414, 576, 720, 960, and 1026, respectively.

First, the pixel PX connected to the data line D receiving the signal from the first data driver 500 is examined. The case where the gradation of the pixel PX is higher than the first-first threshold value G_h is denoted by 01, the case where the gradation of the pixel PX is lower than the first-second threshold value G_l is denoted by 00, (G_h) and the 1-2 threshold value (G_l) is represented by 10.

The first pixel PX connected to the first data line D has a gray level higher than the first threshold value G_h and the second pixel PX has a gray level higher than the first threshold value G_h, Since C (1) has a gray level between the first and second threshold values G_l, 0 is maintained. The first pixel PX connected to the second data line D has a lower gray level than the first threshold value G_l and the second pixel PX has a gray level lower than the first threshold value G_h, Since C (1) has a gray level between the first and second threshold values G_l, 0 is maintained. C (1) is kept at 0 even in the process of comparing the first pixel PX connected to the third through fifth data lines D and the second pixel PX.

The first pixel PX connected to the sixth data line D has a gray level lower than the first-second threshold value G_l and the second pixel PX has a gray level lower than the first- C (1) is changed to 1 because it has a high gradation. The first pixel PX connected to the seventh data line D has a gray level higher than the first threshold value G_h and the second pixel PX has a gray level higher than the first threshold value G_h C (1) is held at 1 because it has a high gradation. The first pixel PX connected to the eighth data line D has a lower gray level than the first-second threshold value G_l and the second pixel PX has a gray level lower than the first-second threshold value G_l C (1) is held at 1 because it has a low gradation. The first pixel PX connected to the ninth data line D has a gray level higher than the first threshold value G_h and the second pixel PX has a gray level higher than the first threshold value G_h C (1) is held at 1 because it has a high gradation. The first pixel PX connected to the tenth data line D has a lower gray level than the first threshold value G_l and the second pixel PX has a gray level lower than the first threshold value G_l C (1) is held at 1 because it has a low gradation.

C (1) is maintained at 1 even in the process of comparing the first pixel PX connected to the eleventh to the twelfth data line D and the second pixel PX.

The second pixel PX connected to the data line D connected to the first data driver 500 and the third pixel PX are connected to the first threshold G_h and the first pixel PX, -2 Compares with the threshold (G_l) to maintain or change C (1). The second pixel PX connected to the sixth data line D has a gray level higher than the first threshold value G_h and the third pixel PX has a gray level higher than the first threshold value G_l C (1) is changed to 2 because it has a low gradation. The second pixel PX connected to the eighth data line D has a gray level lower than the first-second threshold value G_l and the third pixel PX has a gray level lower than the first-first threshold value G_h C (1) is changed to 3 because it has a high gradation. The second pixel PX connected to the eleventh data line D has a gray level higher than the first threshold value G_h and the third pixel PX has a gray level higher than the first threshold value G_l C (1) is changed to 4 because it has a low gradation.

The third pixel PX and the fourth pixel PX connected to the data line D connected to the first data driver 500 are respectively connected to the first threshold value G_h and the first pixel PX, -2 Compares with the threshold (G_l) to maintain or change C (1). The third pixel PX connected to the first, second, third, seventh, eighth and ninth data lines D has a gray level higher than the 1-1th threshold value G_h, The pixel PX has a lower gradation than the first-second threshold value G_l. The third pixel PX connected to the fourth, fifth, sixth, tenth, eleventh and twelfth data lines D has a lower gray level than the first-second threshold G_l, And the fourth pixel PX has a gray level higher than the 1-1th threshold value G_h. Therefore, C (1) is changed to 16.

Next, the pixel PX connected to the data line D receiving the signal from the second data driver 500 will be described.

The first pixel PX and the second pixel PX connected to each data line D connected to the second data driver 500 are divided into a first threshold value G_h and a first And changes C (2) from 0 to 2 as compared with the threshold value G_l.

The second pixel PX and the third pixel PX connected to the data line D connected to the second data driver 500 are connected to the first threshold G_h and the first pixel PX, -2 Change C (2) from 2 to 5 as compared to the threshold (G_l).

The third pixel PX and the fourth pixel PX connected to the data line D connected to the second data driver 500 are respectively connected to the first threshold G_h and the first pixel PX, -2 Change C (2) from 5 to 13 as compared to the threshold (G_l).

4, the gradation of all the pixels of one frame is examined for each data driver 500, so that C (1) is 16 and C (2) is 13.

Next, referring to FIG. 5, when pixels are arranged in a zigzag manner with respect to the data line D, any one of adjacent pixels connected to the same data line D is set to the 1-1th threshold value G_h, And the number of cases in which the other pixel is equal to or less than the 1-2 threshold value G_l will be described as an example.

5 is a graph showing a result of comparing the gradation of each pixel with the 1-1 th threshold value and the 1-2 th threshold value in another display apparatus according to an embodiment of the present invention.

5 includes two data drivers 500. Each data driver 500 is connected to a plurality of data lines D and a plurality of pixels PX ) Are connected.

First, the pixel PX connected to the data line D receiving the signal from the first data driver 500 is examined. Since there are two pixels connected to the first data line D, the pixel connected to the second data line D is examined.

The first pixel PX connected to the second data line D has a gray level higher than the first threshold value G_h and the second pixel PX has a gray level higher than the first threshold value G_h, Since C (1) has a gray level between the first and second threshold values G_l, 0 is maintained. In the same manner, the first pixel PX and the second pixel PX connected to the third through the thirtieth data line D are divided into a 1-1 th threshold value G_h and a 1-2 th threshold value G_l ), C (1) is changed from 0 to 7.

The second pixel PX and the third pixel PX connected to the data line D connected to the first data driver 500 are respectively connected to the first threshold value G_h and the first pixel PX, -2 Change C (1) from 7 to 14 as compared to the threshold (G_l).

The third pixel PX and the fourth pixel PX connected to the data line D connected to the first data driver 500 are connected to the first threshold G_h and the first pixel PX, -2 Change C (1) from 14 to 23 as compared to the threshold (G_l).

Next, the pixel PX connected to the data line D receiving the signal from the second data driver 500 will be described.

The first pixel PX and the second pixel PX connected to each data line D connected to the second data driver 500 are divided into a first threshold value G_h and a first And changes C (2) from 0 to 11 as compared with the threshold value G_l.

The second pixel PX and the third pixel PX connected to the data line D connected to the second data driver 500 are connected to the first threshold G_h and the first pixel PX, -2 Change C (2) from 11 to 15 as compared to the threshold (G_l).

The third pixel PX and the fourth pixel PX connected to the data line D connected to the second data driver 500 are respectively connected to the first threshold G_h and the first pixel PX, -2 Change C (2) from 15 to 19 as compared to the threshold (G_l).

In the display device shown in Fig. 4, all the pixels PX are arranged in the same direction with respect to the data line D, so that they are arranged in the same column for gradation comparison of adjacent pixels connected to the same data line D It is only necessary to compare the gradations of the pixels. In contrast, in the display device shown in Fig. 5, since the pixels PX are arranged in a zigzag manner with respect to the data line D, in order to perform gradation comparison of adjacent pixels connected to the same data line D, The gradations of adjacent pixels must be compared.

Accordingly, even when the pixels PX are arranged in a zigzag manner with respect to the data line D, the positions of the image data are relocated so that the grayscales of the pixels arranged in the same column can be compared with each other . That is, if the pixels PX are arranged in zigzag with respect to the data line D before the number of gradation differences of the image data of the adjacent pixels is equal to or greater than the first threshold value, PX can be rearranged so that they are adjacent to each other in the direction of the data line D.

Referring again to FIG. 3, after comparing and determining the gradation of all the pixels of one frame, C (t) for each data driver is compared with the second threshold C_th. (S140)

Whether C (1) is greater than or equal to a second threshold value (C_th), whether C (2) is greater than or equal to a second threshold value (C_th), and whether C (t) is greater than or equal to a second threshold value do.

When either one of C (1) to C (t) is equal to or larger than the second threshold value (C_th), the gradation of the image data of the next frame is converted and output. (S160) When all of C (1) to C (t) are less than the second threshold value (C_th), normal data is outputted without converting the gradation of the image data of the next frame. (S170)

For example, when the second threshold C_th is set to 14 in the display device shown in FIG. 4, C (1) is set to 16 so that the data driver 500 of any one of the two data drivers 500 Corresponds to the case where C (t) is equal to or greater than the second threshold value (C_th), so that the gradation of the image data of the next frame is converted and output.

5, when C (1) is 23 and C (2) is 19 and C (t) for two data drivers 500 are all equal to or greater than the second threshold value C_th , The gradation of the image data of the next frame is converted and output.

In the above description, the gradation of the image data is converted when any one of C (t) for the plurality of data drivers is equal to or greater than the second threshold value C_th. However, the present invention is not limited to this and other settings are possible . For example, it is also possible to set the gradation of the image data to be converted when 30% or more of C (t) for the plurality of data drivers is equal to or larger than the second threshold value C_th.

If there is image data of the next frame, the converted data or normal data is output, and the process of S110 to S150 is repeated after C (t) is reset to 0 again. On the other hand, when there is no image data of the next frame, the process is terminated. (S150)

Hereinafter, a method of generating converted image data by modifying the gradation of the image data will be described.

if the number of gray levels of image data of two neighboring pixels connected to the same data line is equal to or greater than a first threshold value as a result of comparison and determination of image data of the fth frame, Of the image data.

the gradation of the image data having the gradation exceeding the third threshold value among the image data of the (f + 1) th frame can be corrected to the third threshold value.

Then, if the image data of the (f + 1) th and (f + 2) th frames are compared and determined, the converted image data is continuously output.

if the number of cases in which the difference between the gradations of the image data of two adjacent pixels connected to the same data line is equal to or larger than the first threshold value is less than the second threshold value as a result of comparing and determining the image data of the (f + 3) Th frame, and normal data is output.

Then, if the image data of the (f + 4) th and (f + 5) th frames are the same as the result of the comparison, the normal data is outputted.

An example will be described with reference to Table 1 below. The third threshold value was set to 250. [

Frame number Gradation before correction Gradation after correction f 0-255 0-255 f + 1 0-250 / 251-255 0-250 / 250 f + 2 0-250 / 251-255 0-250 / 250 f + 3 0-250 / 251-255 0-250 / 250 f + 4 0-255 0-255 f + 5 0-255 0-255 f + 6 0-255 0-255

First, in a case where the number of gradation differences of adjacent pixels in the fth frame is equal to or larger than the first threshold value is equal to or larger than the second threshold value, the image data having 0-255 gradations is output without conversion. In the (f + 1) th, (f + 2) th and (f + 3) th frames, the image data having 251-255 gradations is converted into 250 gradations and is output.

if the number of gradation differences of the adjacent pixels in the (f + 3) -th frame is equal to or greater than the first threshold value, the image data having 0-255 gradations in the (f + 4) th frame is output without being converted. Then, normal data is also output in the (f + 5) th and (f + 6) th frames.

Video data having 0-250 gradations outputs normal data without conversion in all frames.

In the above description, when the number of gradation differences of adjacent pixels is equal to or larger than the first threshold value is equal to or greater than the second threshold value, the gradation of the image data having gradations exceeding the third threshold value in the next frame is modified to the third threshold value However, the present invention is not limited to this, and image data can be converted by another method.

Hereinafter, another method for generating the converted image data by modifying the gradation of the image data will be described.

In the above description, the gradation difference of the adjacent pixels is compared and determined and whether the image data of the next frame is converted or not is determined. However, in another method described below, the gradation of the image data having the gradation exceeding the third threshold value It can be sequentially reduced for multiple frames and modified to a third threshold.

if the number of cases in which the gradation difference of the adjacent pixels in the fth frame is equal to or larger than the first threshold value is equal to or greater than the second threshold value, the gradation of the image data having the gradation exceeding the third threshold value is defined as f + Th frame, and corrects it to the third threshold value.

if the number of cases in which the gradation difference of the adjacent pixels between the (f + 1) -th frame and the (f + 5) -th frame is equal to or larger than the first threshold value is less than the second threshold value, the gradation of the image data having the gradation exceeding the third threshold , And sequentially corrects the data to normal data.

if the number of gradation differences of the adjacent pixels in the (f + 6) -th frame is equal to or larger than the first threshold value is less than the second threshold value, the gradation of the image data having gradations exceeding the third threshold value is defined as f + The data is sequentially changed from the converted data to the normal data during five frames consisting of the + 11th frame.

if the number of gradation differences of the adjacent pixels between the (f + 7) th frame and the (f + 11) th frame is greater than or equal to the first threshold value, the correction process to the normal data is stopped, Conversion proceeds sequentially.

An example will be described with reference to Table 2 below. The third threshold value is set to 250, and the conversion of image data is set to be performed by one gray level in one frame.

Frame number Gradation before correction Gradation after correction f 0-255 0-255 f + 1 0-254 / 255 0-254 / 254 f + 2 0-253 / 254-255 0-253 / 253 f + 3 0-252 / 253-255 0-252 / 252 f + 4 0-251 / 252-255 0-251 / 251 f + 5 0-250 / 251-255 0-250 / 250 f + 6 0-250 / 251-255 0-250 / 250 f + 7 0-251 / 252-255 0-251 / 251 f + 8 0-252 / 253-255 0-252 / 252 f + 9 0-253 / 254-255 0-253 / 253 f + 10 0-254 / 255 0-254 / 254 f + 11 0-255 0-255

First, in a case where the number of gradation differences of adjacent pixels in the fth frame is equal to or larger than the first threshold value is equal to or larger than the second threshold value, the image data having 0-255 gradations is output without conversion. and in the (f + 1) -th frame, the image data having 255 gradations is converted into 254 gradations and outputted. At this time, the image data having 0-254 gradations are output without outputting normal data. and in the (f + 2) -th frame, the image data having 254-255 gradations is converted into 253 gradations and output. At this time, the image data having 0-253 gradation is not converted but normal data is output. and in the (f + 3) -th frame, the image data having 253-255 gradations is converted into 252 gradations and outputted. At this time, the image data having 0-252 gradations are not converted and normal data is output. and in the (f + 4) -th frame, the image data having 252-255 gradations is converted into 251 gradations and output. At this time, the image data having 0-251 gradations are not converted and normal data is output. and in the (f + 5) th frame, the image data having 251-255 gradations is converted into 250 gradations and output. At this time, the image data having 0-250 gradations are not converted and normal data is output.

If the number of the gradation differences of the adjacent pixels in the (f + 1) th frame to the (f + 4) th frame is equal to or larger than the first threshold value, In contrast, if the number of gradation differences of the adjacent pixels between the (f + 1) -th frame and the (f + 4) -th frame is equal to or larger than the first threshold value is less than the second threshold value, the sequential conversion of the image data is stopped, Proceed with the recovery process for outputting the data.

If the number of gradation differences of the adjacent pixels in the (f + 6) th frame is equal to or larger than the first threshold value is less than the second threshold value, the image data having 252-255 gradations in the (f + 7) th frame is converted into 251 gradations and output. and in the (f + 8) -th frame, the image data having 253-255 gradations is converted into 252 gradations and outputted. In the (f + 9) th frame, the image data having 254-255 gradations is converted into 253 gradations and output. In the (f + 10) th frame, the image data having 255 gradations is converted into 254 gradations and output. In the (f + 11) -th frame, normal data is output without conversion of image data.

If the number of cases in which the gradation difference of the adjacent pixels in the (f + 7) th frame to the (f + 10) th frame is equal to or larger than the first threshold value is less than the second threshold value, In contrast, if the number of cases in which the gradation difference between the f + 7th frame and the f + 10th frame is equal to or greater than the first threshold value is greater than or equal to the second threshold value, the recovery process for outputting the normal data is stopped And sequentially performs the conversion of the video data.

Hereinafter, another example will be described with reference to Table 3 below. The third threshold value is set to 250, and the conversion of the image data is set to be performed by one gray level in two frames.

Frame number Gradation before correction Gradation after correction f 0-255 0-255 f + 1 0-255 0-255 f + 2 0-254 / 255 0-254 / 254 f + 3 0-254 / 255 0-254 / 254 f + 4 0-253 / 254-255 0-253 / 253 f + 5 0-253 / 254-255 0-253 / 253 f + 6 0-252 / 253-255 0-252 / 252 f + 7 0-252 / 253-255 0-252 / 252 f + 8 0-251 / 252-255 0-251 / 251 f + 9 0-251 / 252-255 0-251 / 251 f + 10 0-250 / 251-255 0-250 / 250 f + 11 0-250 / 251-255 0-250 / 250

First, when the number of gradation differences of the adjacent pixels in the fth frame is equal to or greater than the first threshold value is equal to or greater than the second threshold value, image data having 0-255 gradations are not converted in the fth frame and the f + And outputs it as it is. In the (f + 2) -th frame and the (f + 3) -th frame, the image data having 255 gradations is converted into 254 gradations and output. and in the f + 4th frame and the (f + 5) th frame, the image data having 254-255 gradations is converted into 253 gradations and outputted. In the (f + 6) -th frame and the (f + 7) -th frame, the image data having 253-255 gradations is converted into 252 gradations and output. In the f + 8th frame and the (f + 9) th frame, the image data having 252-255 gradations is converted into 251 gradations and outputted. In the (f + 10) -th frame and the (f + 11) -th frame, the image data having 251-255 gradations is converted into 250 gradations and output.

If the number of the gradation differences of the adjacent pixels in the (f + 1) th frame to the (f + 10) th frame is equal to or larger than the first threshold value, Alternatively, if the number of cases in which the gradation difference of the adjacent pixels between the (f + 1) th frame and the (f + 10) th frame is equal to or larger than the first threshold value is less than the second threshold value, the sequential conversion of the image data is stopped, Proceed with the recovery process for outputting the data.

Next, a description will be given of a main pattern for converting image data, which is determined to cause overheating of the data driver in the display device and the driving method thereof according to an embodiment of the present invention.

6 to 13 are diagrams showing various patterns that cause overheating of the data driver. A pixel displaying a hatched portion has a gradation close to the minimum gradation, and a pixel not displaying a hatched portion has a gradation close to the maximum gradation.

FIG. 14 is a graph showing a plurality of patterns of temperatures according to the number of data lines connected to the data driver.

6 is a horizontal stripe pattern in which the pixels belonging to the first row and the third row have gradations close to the maximum gradation, and the pixels belonging to the second row and the fourth row have gradations close to the minimum gradation. If the pixels are arranged in the same direction with respect to the same data line, the gradation difference between adjacent pixels connected to the same data line has a very large value. Therefore, it is possible to cause the data driver to overheat.

FIG. 7 shows that six consecutive pixels among the pixels belonging to the same row have gradations close to the maximum gradation, and the next six pixels have gradations close to the minimum gradation. Further, the pixels having the grayscale close to the maximum grayscale and the pixels adjacent to the row direction have the grayscale close to the minimum grayscale. In addition, a pixel having a gradation close to the minimum gradation and a pixel adjacent to the column direction have a gradation close to the maximum gradation.

8 is a checker pattern in which three consecutive pixels among the pixels belonging to the same row have gradations close to the maximum gradation, and the next three pixels have gradations close to the minimum gradation. In addition, a pixel having a gradation close to the maximum gradation and a pixel adjacent to the column direction have a gradation close to the minimum gradation, and a pixel having a gradation close to the minimum gradation and a pixel adjacent to the column direction have gradations close to the maximum gradation.

9 shows a subcatcher pattern in which pixels having gradations close to the maximum gradation and pixels having gradations close to the minimum gradation are alternately repeated in the column direction and the row direction.

In Fig. 10, two consecutive pixels among the pixels belonging to the same row have gradations close to the maximum gradation, and the next two pixels have gradations close to the minimum gradation. In addition, a pixel having a gradation close to the maximum gradation and a pixel adjacent to the column direction have a gradation close to the minimum gradation, and a pixel having a gradation close to the minimum gradation and a pixel adjacent to the column direction have gradations close to the maximum gradation.

11, in the first row and the second row, the three pixels have a gradation near to the maximum gradation, and the next three pixels have a pattern repeated so as to have a gradation close to the minimum gradation. In the third row and the fourth row, the three pixels have a gradation close to the minimum gradation, and the next three pixels have a pattern repeated so as to have a gradation close to the maximum gradation.

6 to 10, video data applied to pixels connected to one data line swings every pixel, whereas in FIG. 11, swings are performed for each of two pixels, so that overheating of the data driver is relatively less Lt; / RTI > However, even in this case, since the frequency with which the gradation difference of adjacent pixels connected to the same data line is large is high, the data driver will overheat.

12 shows a pattern in which pixels having gradations nearest to the maximum gradation and pixels having gradations close to the minimum gradation are repeated in the first row and the second row. The third row and the fourth row have a pattern in which a pixel having a gradation close to the minimum gradation and a pixel having a gradation close to the maximum gradation are repeated.

13 is a sub-vertical stripe pattern in which the pixels belonging to the odd-numbered columns have a grayscale close to the maximum grayscale, and the pixels belonging to the even-numbered column have grayscales close to the minimum grayscale.

In the case of the sub-vertical stripe pattern, if the pixels are arranged in the same direction with respect to the same data line, the gradation difference between adjacent pixels connected to the same data line is very small, so that the data driver does not overheat. However, when a sub-vertical stripe pattern is applied to a display device in which pixels are arranged in a zigzag manner on the basis of the same data line, the gradation difference between adjacent pixels connected to the same data line is very large, .

The degree of overheating of the data driver according to the pattern type through the graph shown in FIG. 14 will be described below. In Fig. 14, all the patterns indicate the case where the pixels are arranged in the same direction with respect to the same data line.

In a pattern in which the entire screen is black, the temperature of the data driver is the lowest. In the sub-vertical stripe pattern and the pattern in which the entire screen is black, the temperature of the data driver is higher than that of the black pattern, but the degree of overheating is not enough. Next, the temperature of the data driver gradually rises in the order of the sub-checker pattern, the checker pattern, and the horizontal stripe pattern, and the data driver may overheat if the pattern continues for a long time.

According to the display device and the driving method thereof according to an embodiment of the present invention, it is possible to detect a pattern in which overheating of the data driver is likely to occur.

Hereinafter, how the temperature of the data driver can be lowered by converting and outputting image data when such a pattern is detected will be described with reference to FIG.

15 is a graph showing the temperature of the data driver according to the correction of the maximum gradation in a horizontal stripe pattern in which rows composed of pixels having the maximum gradation and rows composed of pixels having the smallest gradation are alternately repeated.

As shown in FIG. 15, the temperature of the data driver is measured at 188 degrees when the row of pixels having 255 gray scales and the row of pixels having 0 gray scale are alternately repeated. As the maximum gradation gradually decreases from 255 gradations, it can be seen that the temperature of the data driver is also lowered. When the maximum gradation is lowered to 227 gradations, the temperature of the data driver is measured at 155 degrees.

For example, if the pixels having 255 gradations in the horizontal stripe pattern are converted to have 232 gradations, the temperature of the data driver can be lowered by about 30 degrees. The luminance change of the screen due to such gradation correction is not enough to be visually recognized. Also, in the case where the visibility of the luminance change is concerned, it is possible to prevent the image data from being converted sequentially for a plurality of frames as described above.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, Of the right.

300: display panel 400: gate driver
500: Data driver 600: Signal controller
610: Data conversion unit 612: Data mapping unit
614: Data comparison unit 616:

Claims (20)

A display panel including a plurality of gate lines, a plurality of data lines, and pixels connected to the gate lines and the data lines;
A gate driver for supplying a gate signal to the gate line;
A data driver for supplying a data signal to the data line; And
And a signal controller for controlling the gate signal and the data signal,
Wherein the signal control unit comprises:
And a data conversion unit for converting the gradation of the image data when a difference between gradations of image data of two adjacent pixels connected to the same data line among the plurality of data lines is equal to or greater than a first threshold value,
Display device.
The method according to claim 1,
Wherein the data conversion unit comprises:
A data comparator for counting the number of times when a difference between gradations of image data of two adjacent pixels connected to the same data line is equal to or greater than the first threshold value and determining whether the number is equal to or greater than a second threshold value; And
And a gradation correcting section for converting the gradation of the image data when the number is equal to or greater than the second threshold value.
Display device.
3. The method of claim 2,
Wherein the data comparison unit comprises:
When the grayscale of any one of the two adjacent pixels is equal to or greater than a first threshold value and the grayscale of the other pixel is equal to or less than a first threshold value,
When the grayscale of one of the pixels adjacent to each other is equal to or less than the first threshold value and the grayscale of the other pixel is equal to or greater than the first threshold value,
And determines that a difference between gradations of image data of two adjacent pixels is equal to or greater than a first threshold value,
Display device.
3. The method of claim 2,
Wherein the gradation correcting unit comprises:
When the number is greater than or equal to the second threshold value,
Correcting the gradation of the image data having the gradation exceeding the third threshold value to the third threshold value,
Display device.
5. The method of claim 4,
Wherein the gradation correcting unit comprises:
And sequentially modifying the gradation of the image data having the gradation exceeding the third threshold value for a plurality of frames to the third threshold value,
Display device.
3. The method of claim 2,
Wherein the data comparison unit comprises:
The gradation of the entire image data of one frame is compared to count the number of gradations,
Wherein the gradation correcting unit comprises:
And converting the gradation of the image data of the next frame when the number is greater than or equal to the second threshold value,
Display device.
3. The method of claim 2,
The data driver includes a plurality of data drivers,
Wherein the data comparator counts the number for each of the plurality of data drivers,
Display device.
8. The method of claim 7,
Wherein the gradation correcting unit converts the gradation of the image data when the number of the data drivers in any one of the plurality of data drivers is equal to or greater than the second threshold,
Display device.
3. The method of claim 2,
Wherein the data comparison unit comprises:
When the pixels are arranged in a zigzag manner with respect to the data lines,
And comparing the difference of gradations of image data of two pixels adjacent to each other in the diagonal direction to count the number of gradations of the image data equal to or larger than the first threshold value,
Display device.
3. The method of claim 2,
Wherein the data conversion unit comprises:
Further comprising a data mapping unit for rearranging image data of two pixels adjacent to each other in a diagonal direction so as to be adjacent to each other in the direction of the data line when the pixels are arranged in a zigzag manner with respect to the data line.
Display device.
Counting the number of times when a difference between gradations of image data of two adjacent pixels connected to the same data line among the plurality of data lines is equal to or greater than a first threshold value;
Determining whether the number is greater than or equal to a second threshold value;
Converting the gradation of the image data if the number is greater than or equal to the second threshold value; And
And outputting the converted image data.
A method of driving a display device.
12. The method of claim 11,
And outputting the image data without converting the gradation of the image data when the number is less than the second threshold value,
A method of driving a display device.
12. The method of claim 11,
In the step of counting the number of cases in which the difference in gradation of the image data of the two adjacent pixels is equal to or greater than the first threshold value,
When the grayscale of any one of the two adjacent pixels is equal to or greater than a first threshold value and the grayscale of the other pixel is equal to or less than a first threshold value,
When the grayscale of one of the pixels adjacent to each other is equal to or less than the first threshold value and the grayscale of the other pixel is equal to or greater than the first threshold value,
And determines that a difference between gradations of image data of two adjacent pixels is equal to or greater than a first threshold value,
A method of driving a display device.
12. The method of claim 11,
In the step of converting the gradation of the image data,
When the number is greater than or equal to the second threshold value,
Correcting the gradation of the image data having the gradation exceeding the third threshold value to the third threshold value,
A method of driving a display device.
15. The method of claim 14,
In the step of converting the gradation of the image data,
And sequentially modifying the gradation of the image data having the gradation exceeding the third threshold value for a plurality of frames to the third threshold value,
A method of driving a display device.
12. The method of claim 11,
In the step of counting the number of cases in which the difference in gradation of the image data of the two adjacent pixels is equal to or greater than the first threshold value,
The gradation of the entire image data of one frame is compared to count the number of gradations,
In the step of converting the gradation of the image data,
And converting the gradation of the image data of the next frame when the number is greater than or equal to the second threshold value,
A method of driving a display device.
12. The method of claim 11,
Wherein the plurality of data lines are connected to a plurality of data drivers,
In the step of counting the number of cases in which the difference in gradation of the image data of the two adjacent pixels is equal to or greater than the first threshold value,
Counting the number for each of the plurality of data drivers,
A method of driving a display device.
18. The method of claim 17,
In the step of converting the gradation of the image data,
And converting the gradation of the image data when the number of the data drivers in any one of the plurality of data drivers is equal to or greater than the second threshold,
A method of driving a display device.
12. The method of claim 11,
Wherein the display device includes a plurality of pixels connected to the data line,
In the step of counting the number of cases in which the difference in gradation of the image data of the two adjacent pixels is equal to or greater than the first threshold value,
When the plurality of pixels are arranged in a zigzag manner with respect to the data line,
And comparing the difference of gradations of image data of two pixels adjacent to each other in the diagonal direction to count the number of gradations of the image data equal to or larger than the first threshold value,
A method of driving a display device.
12. The method of claim 11,
Wherein the display device includes a plurality of pixels connected to the data line,
Before the step of counting the number of cases in which the difference in gradation of the image data of the two adjacent pixels is equal to or greater than the first threshold value,
And rearranging the image data of two pixels adjacent to each other in the diagonal direction so as to be adjacent to each other in the direction of the data line when the plurality of pixels are arranged in a zigzag manner with respect to the data line.
A method of driving a display device.

Images